Technically co-authors are all the authors on the paper. Some papers specify if more than one author has put in an equal contribution.(e.g. author X*, author Y* author Z. *-these authors contributed equally to this work).

Usually the citation will be the first author only, but it depends on the citation style you use.

Technically co-authors are all the authors on the paper. Some papers specify if more than one author has put in an equal contribution.(e.g. author X*, author Y* author Z. *-these authors contributed equally to this work).

Usually the citation will be the first author only, but it depends on the citation style you use.

but in most citation styles, the equal contributors dont get cited at all (e.g. X et al 2013 instead of X, Y, Z et al 2013)

sure every paper and even short communication or abstract in proceedings is important for your CV, even if only second, third or 20th author...in my CV I always write my name in bold in the list with such stuff

One must presume that long and short arguments contribute to the same end. - Epicurus...except casandra's that did belong to the funniest, most interesting and imaginative (or over-imaginative?) ones, I suppose.